1. Field of the Invention
The present invention relates to an ink-jet recording apparatus which supplies an ink-jet head with ink while removing air dissolved in ink not to affect ejection of ink, a method of removing air of an ink-jet recording apparatus, and an air removing device.
2. Description of the Related Art
A conventional ink-jet recording apparatus pressurizes ink in a pressure chamber and ejects ink as an ink drop. An ejected ink drop is adhered to a recording medium at a certain distance from an ink jet head. As a result, an image is formed.
When a nozzle is clogged or an air bubble is generated in a pressure chamber, ink may not be ejected from a nozzle. If ink is not ejected from a nozzle, printing on a recording medium fails.
A filter is provided before an ink-jet head to remove dust mixed in ink and causes clogging of a nozzle.
When an air bubble is generated in a pressure chamber, an ink pressurizing force is lowered. As a result, an ink drop ejecting force is lowered. Thus, it is necessary to remove air dissolved in the ink supplied to the ink-jet head.
Air removing device and method are proposed to remove air dissolved in ink.
For example, U.S. Pat. No. 5,341,162 proposes a device for removing air dissolved in liquid by heating liquid.
Jpn. Pat. Appln. KOKAI Publication No. 11-114309 proposes a method of heating a tube connected to an air removing device and guiding the heated liquid to the air removing device.
The device of U.S. Pat. No. 5,341,162 increases an air removing capacity by heating, but releases dissolved air into the atmosphere. Thus, an air removing efficiency is bad compared with an enclosed type air removing device.
A heating means such as a heater is placed directly in liquid in this device.
This configuration makes maintenance of a heating means troublesome.
The device of Jpn. Pat. Appln. KOKAI Publication No. 11-114309 increases an air removing capacity by guiding heated liquid to an air removing device. But, the liquid ejected from the air removing device is cooled down to a previous temperature in the next process. Generally, solubility of air in liquid decreases when a temperature increases, and increases when a temperature decreases.
Thus, when the liquid ejected from the air removing device is cooled, air dissolves in liquid and the amount of dissolved air increases.